Detectives interviewed 40-50 people while investigating a September 2012 arson at Loftis Middle School before arresting two 17-year-olds, Hamilton County Sheriff's Office detective David Sowder said today.

Numerous search warrants were executed, Sowder said.

"This was a crime of opportunity, and we're very fortunate to make the arrests we have," he said.

Sowder said the investigation is ongoing and he could not give details about what led authorities to arrest the teens.

Lee McDade, assistant superintendent at Hamilton County Schools, described the arrest as "a big relief" for the school system.

On Sept. 17, Dallas Bay Volunteer firefighters responded to a fire call at Loftis Middle, located on Camp Columbus Road in Hixson.

Firefighters extinguished a fire that was contained to one room. Hamiton County Sheriff's Office and Red Bank Police SWAT teams had to clear the building, but no one was found, according to authorities.

A $10,000 award was offered in November for information leading to the arrests of those responsible.

ATF special agent Darryl Hill said it's unclear whether anyone will receive the reward. He said authorities are waiting until all arrests are made and the case is prosecuted.

Investigators found broken windows, ruined classrooms and blinds ripped off windows. The main office inside the school was ransacked and, when the sprinkler system was triggered, a dozen classrooms sustained water damage.

Multiple fires had been set throughout the building. Cash and electronic equipment was taken from the school, according to authorities.